Foremost amongst the many technical challenges facing manufacturers of semiconductor sensors/detectors is the need to avoid false alarms. A common cause of false alarms is the presence in the vicinity of the detector of a gas (so-called interference gas) to which the detector responds in a way similar to that for the target gas. Another cause is a change in relative humidity. It is this unfortunate sensitivity of gas-sensitive semiconductors to the vapor pressure of water that has resulted in the sensor chips being run at temperatures of 150° C. or higher. Even then, problems associated with changes in relative humidity still pertain. With increasing demands placed on the performance of carbon monoxide sensors/detectors for domestic use, there is a need to reduce the sensitivity to water vapor still further.